Recently, the need for increased amounts of bandwidth capacity has become clear in virtually every category of telecommunications, including small-sized business, medium-sized business, and large enterprises, residential users that watch television, surf the web, talk on wireline and wireless telephones, cell towers that are expanding into G3 (third generation) and G4 (fourth generation) wireless data networks, wireless access points that are expanding from retail hot-spots to larger mesh-based coverage areas, etc. The demand for capacity expansion is seen in literally areas, and furthermore, this demand is growing significantly in the upstream (or “user-generated”) direction where, in the past, Internet/web-based information and television services have been very asymmetric in the downstream direction. The surge in user-generated content, including the publishing of home video content and the like, has exacerbated the upstream capacity issue.
Another axis of capacity expansion is in the proliferation of devices, both fixed and mobile, that will be sending and receiving information, from hand-held to vehicle-based to home-based to office-based. As these new devices expand from being one-service devices (e.g. voice only, data only, television only) to multi-service devices (integrated voice/data/video devices), the consumption of bandwidth capacity is forecast to grow dramatically, again in both the downstream and upstream directions.
The transition to Ethernet as the basis for transport of information across long distance and metropolitan networks is underway. This is causing a gradual transition away from ATM and TDM-based networks to Carrier Ethernet-based networks. Similarly, in the customer premises, be they business offices or residential homes, there is a large scale transition to Ethernet-based in-premise networks. This leaves the last remaining “Ethernet gap” in the last mile access networks. And now these access networks are beginning their transition to carrier Ethernet. For telephone companies, this means fiber-to-the-premises (FTTP) in the more densely populated areas, where fiber construction can be cost-justified. For the less densely populated areas, some form of fiber-to-the-curb (FTTC) or fiber-to-the-node (FTTN) architectures are under construction. A common thread in all of these networks is that Internet protocol (IP) packets using Ethernet-based networking protocols are being used to carry information of any type across many different types of media, including fiber, coaxial cable, twisted pair telephone wire, cat-5 or cat-6 Ethernet cable, WiFi, WiMax, and free space optics.
It is necessary, therefore, to have switches that can cross-connect (i.e. switch) packets from one type of physical medium to another. It is also important that these switches have the ability to be located outdoors. Some of the drivers for outdoor switching are as follows. First, ADSL and VDSL networks of all varieties are very distance-dependent to determine the performance, and thus, the capacity, of their transmissions. By moving the optical-to-copper conversion/aggregation point deeper into the network (i.e. outdoors), the distance to be transmitted over the copper wires is reduced, thereby increasing the bandwidth performance on the copper pair. Second, switches have traditionally been located in air-conditioned and thermally-controlled “brick-and-mortar” buildings, requiring the costs of real estate, maintenance, power for heating and air-conditioning, zoning for construction, etc. Outdoor switches, on the other hand, can be mounted on telephone pole strands, in street cabinets and pedestals, in underground vaults, as well as in indoor settings. The flexibility of using outdoor locations dramatically reduces the cost of housing and maintaining the switches. Third, traffic management of information flows can be significantly improved if the intelligent switching device is located nearer to the actual location of capacity usage. Bandwidth distribution in the downstream and bandwidth contention resolution in the upstream are best done at the ingress point of the access network rather than on the opposite side of the access network, which needlessly consumes capacity across the network.